Fastening means



' Feb. 16, 1943. N--' 2,311,326

FASTENfNG MEANS- Filed Nov. 25, 1940 v INVENTOR .Dzlmitriair/div ATTORNEY Patented Feb. 16, 1943 orurep stares rarest car ies FASTENING MEANS Dimitri Birkin, Philadelphia, Pa. Application November'25, 1940, Serial No. 367,102

1 3 Claims.

The present invention relates in general to the art of joining flexible sheet material to nonflexible parts and more particularly to a joint structure for securing a covering of flexible sheet material to a non-flexible or substantially rigid frame or body element as in the upholstering or covering of the seats and backs of chairs, or the seats, head lining and other portions of auto mobiles, rail cars and the like.

The joint to which the present invention relates is an improvement upon that general type in which the flexible material in the form of a fabric covering is held to a frame member by a loop or hem on the fabric extending into a channel in which it is held by means of a looking or spreader element placed within the loop to spread and lock the latter within the channel. Heretofore it has been proposed to have the loop extend into the channel through a narrow slot and expanded within the channel by a spreader in the form of a rope or thick cord pulled through the loop or hem Within the channel. While such known form of joint provides a substantially positive fastening, it would not be readily applicable to joints which change their direction through a curvature of relatively short radius, because of the increased frictional resistance oifered to the pulling through of the spreader rope around one or several such sharp curves.

It is therefore an important object of the invention to overcome the above difficulties and provide an improved joint of the general type mentioned, which can be used along lines with curvatures of relatively short radius.

Another object of the invention is to provide a, simple, compact joint structure and method of assembling the same, which will make for simplicity and increased speed in the application of upholstery or other covering to a frame or body structure.

Another object is to provide a joint for connecting a covering of flexible material to a nonflexible frame member which may be disassembled and reassembled Where required, as for cleaning and other purposes without wear, strain, or injury to either the flexible covering material or the frame element.

A further object is to provide a joint structure which will afford a positive connection between the flexible covering material and the frame as distinguished from the usual frictional hold obtained by Wedging or springing the material with a filler into a channel or by tacking to a support so held in a channel.

A still further object is to provide a machine for carrying out the method of assembling the improved joint With facility and dispatch.

Various other objects and advantages of the invention will be apparent from a perusal of the following specification and the drawing accompanying the same,

In the drawing:

Fig. 1 is a fragmentary perspective View partly in section, showing the improved joint applied to a sheet metal seat frame.

Fig. 2 is a fragmentary bottom perspective view, partly in section, of a sheet metal frame and cushion, showing the joint in process of being assembled.

Fig. 3 is a perspective view of the machine for feeding the helical spring locking member in the assembling of. the joint.

Fig. 4 is a transverse section through the feeding machine taken as indicated by the line 4-4 on Fig. 3. a

Fig. 5 is a fragmentary sectional view showing the improved joint applied to a solid frame element of wood, plastic compound, or other suitable material.

Referring in detail to the drawing, and first to Fig. 1, this shows the joint applied to a sheet metal cushion-seat frame for holding a flexible seat covering to the frame. Here the sheet metal body or frame element H] has formed integrally therewith about its periphery, a channel portion H closed except for a relatively narrow slot opening I2 near the outer peripheral edge of the frame. The flexible, sheet material [3 forming the sides of the covering of a suitable cushion seat, not shown, is provided with a tubular hem l 4 held closed by the stitching l 5. This-hem, which continues around the entire lower edge of the sides of the covering, extends through the narrow slot I 2 into the channel I l in which it is positively held against withdrawal through the slot by a helicalspring locking element l6 inserted longitudinally through the hem within the channel.

The feeding of the flexible locking element into the hem within the channel is effected as shown in Fig. 2 through an opening I? in the wall of the channel and into the hem I4 through a slit l8 in the hem. I have discovered that it is not necessary to thread a lead-cord or pull-string through the hem, or to insert the entire hem or even a large portion of its length into the channel before insertion of the locking element It, and that it suffices to insert merely a short length of the hem beginning at the slit l8 before inserting the helical spring locking element. After insertion of a small portion of the helical spring into the hem as shown in Fig. 2, the feeding of the spring through the hem may be continued by applying to the spring a rotation in a direction tending to thread the helix forward. As the helical spring locking element is thus fed forward along through the hem, it draws successive portions of the hem through the slot into the channel, continuing along through the hem within the channel, readily rounding the corners such as the corner IS in Fig. 1, until the forward end reaches a point in the channel at or near the opening It has been found that this operation takes place freely and without the along with it or otherwise tending to pucker or. gather the material. This advantageous result is believed to be due helix dragging the hem I.

to a threading of the helix through the hem in the manner of a screw, so that Y the helix moves through with little or no tendency to push or pull the hem along the channel. 'After the leading end of the locking element It having completed its circuit, arrives at or near the point of entry, the remainder, if any, of the locking element outside of the channel is severed close to the entranceopening l1 and the severed end worked into the hem and channel to complete the joint. This step of severing a remaining uninserted portion of the locking element may of course, be avoided in thequantity production of identical articles by using predetermined lengths. The joint thus assembled may be as readily disassembled for renewal of the fabric for cleaning, or for otherpurposes, by a reversal of th assembling process. Thus, to disassemble the joint it is necessary simply to withdraw the severed end of the locking element l6 through the entrance opening I1 and continue to withdraw the entire looking element by applying a rotation thereto opposite to that utilized in the assembling. It is to be noted here that instead of providing the special entrance opening [1, a portion of the slot |2, in the case of a sheet metal frame as in Fig. 3, may be temporarily opened to permit passage of the locking element.

The discovery that the locking element as here provided may be readily inserted into the hem within the channel, makes it possible to use a relatively extremely narrow slot for the entrance of the hemmed margin of the covering material, with'the result that the hem greatly expanded beyond the width of the slot by the locking element I6, is positively locked within the channel. Preferably the width of the slot is made little more than that necessary to permit the flat, collapsed hemtobe drawn through the slot into the channel by movement of the locking element into the hem. However, inasmuch as the helical spring, locking member need be only transversely flexible, and is notrequired to be diametrically compressed at any time, it may be made of hard, strong stock which will insure against distortion in assembling and disassembling, and against probability of its being sprung through the slot even where the slot is relatively wide, so long as the slot is narrower than the spring covered by the hem;

,A further advantage of ture and'method of assembling is that the channel maybe closed or inaccessible at the end opposite the entrance end inasmuch as there is no necessity for the use of a pilot-string or leading cord. The 'joint thus lends itself to use in situations where but one place along the line of attachment is readily accessible.

To facilitate rapid assembly of the joint, I provide the helix feeding apparatus shown in Figs. 3 and 4. This comprises a frame member the present joint struc- ,or raised portions 3|,

. -volutions will 21 between the raised portions.

- crank 35.

having a base portion 2| with vertically extending, bearing walls 22, 23, and 24. Between the bearing walls 22and 23 are mounted a set of three cylindrical rolls consisting of a pair of driving rolls 25 and 26, and a feed roll 21 carried on shafts 28, 29, and 30, respectively, journaled in the bearing walls 22 and 23. The rolls are arranged with their axes parallel and are spaced apart laterally a distance just sufficient to hold between them the helical spring, locking member It, in frictional engagement therewith. The feed roll 21 is provided with annular, circumferential corrugations which latter are evenly spaced to receive between them the helical surface portions or convolutions of the helical spring locking member Hi. The spacing of the rolls is such that the outer surface of the helical conbear against the surface of the roll All three of the rolls are arranged to be rotated in the same direction by an extension of their shafts through the bearing wall 23 into the space between the latter and the bearing wall 24, where they are provided each with a driven gear 32 fixed thereto. While but two of the gears 32 are here shown, those for the shafts 28 and 30, it will be understood that the driven gear for the shaft 29 occupies a'position in the space between the bearing walls 23 and 24 similar to the gears 32 shown. Mounted centrally of the group of three driven'gears 32 is a driving gear all three of thedriven gears 32 and secured to a driving shaft 34 journaled in the bearing walls 23 and 24 and provided on the outside with a driving Suitable openings 36 and 31 are provided in the bearing wall 22 and base portion 2|,

respectively, for passage of the helical spring through the machine.

In the operation of this machine for assembling a joint, using a right-hand spiral (one in which the convolutions rotate clockwise in advancing away from the operator) as shown in the drawing, the leading end 38 of the helix bent backward or otherwise rounded or blunted at the tip end as shown in Figs. 2 and 3, is led into the machine through the opening 31 and between the rolls 25, 25, and 21, with a right-hand twisting motion to thread the convolutions into the spaces between the circumferential corrugations 3| of the feed roll 21 and along between the rolls for at least a portion of their length whereupon a turning of the crank 35 in a clockwise direction, will cause the helical spring to be fed on along the rolls and out through the opening 36. It will be clear from Fig. 3 how the crank turning in a clockwise direction operates through the central driving gear 33 and driven gears 32 to rotate the rolls 25, 26, and 21 in a counter-clockwise direction, and consequently rotate the helical spring which is in frictional engagement with the rolls, in a clockwise direction. Due to the fact that the annular grooves or spaces between the corrugations 3| remain in a fixed plane, the rotating helix is forced to advance axially and out through the opening 36.

After a convenient length of the helical spring is propelled from the machine, the leading end is inserted by hand through the opening I1 and the slit l8 into a short portion of the hem H within the channel ll. Continued rotation of the crank 35 will now effect a continuous rotation and forward urge of the helix causing the latter to thread its way on through the hem within the channel, rounding the corners such-as the corner l9, Fig. l, to complete its circuit by arrival 33, in mesh with at or near the slit I8 and within the channel near the entrance opening IT. The portion of the helix thus fed into the channel is then severed from the remainder at a point near the opening I? and the severed end worked into the hem and channel to complete the joint. This working in of the end may be without disturbing the placement of the spring as a whole, and then severing it near the opening l I, so that the severed end will tend to withdraw itself into the channel.

To disassemble the joint it is necessary only to withdraw a portion of one end of the helical spring by exerting a slight pull thereon accompanied by a left-hand rotation until a small portion has been withdrawn sufficient to extend into the machine through the opening and between the rolls in mesh with some of the annular corrugations of the feed roll. After such portion is started into the machine between the rolls, the crank 35 is turned to feed the helix back through the machine and out of the hem and channel.

This method of assembly obviates the necessity of having the entire required length of helical spring formed before commencing the step of assembling the joint and makes it possible to provide for the formation of the helical spring from a piece of straight wire as it enters the channel and hem, whereby the steps of formation of the spring and assembly of the joint may be combined with obvious economies. Any known or other suitable helix forming device capable of forming the spring and discharging the same with a forward rotary motion into the channel through the entrance opening I 1, may be utilized for this purpose.

While I have herein shown and described a specific embodiment of my invention for the sake of disclosure, it is to be understood that the ible sheet with a hem,

3 invention is not limited to such specific embodiment but contemplates all such modifications and variants thereof as fall fairly within the scopeof the appended claims.

What I claim is:

1.The method of joining a flexible sheet to a substantially non-flexible member which comprises providing the non-flexible member with a channel having a slot opening, providing the flexible sheet with a hem, placing the hem for a small portion of its length through the slot into the channel, and progressively threading a helical spring into the hem within the channel by applying to the helical spring a rotation in a direction tending to feed the helical spring through the hem.

2. The method of joining a flexible sheet to a substantially non-flexible member which comprises providing the non-flexible member with a channel having a slot opening, providing the flexplacing the hem for a serting a flexible helical locking member direct- 1y into and through the hem side of the slot by rotating the locking member in a direction tending to feed the same in the forward direction.

DIMITRI BIRKIN. 

